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virtio: simplify config mechanism.

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Previously we used a type/len pair within the config space, but this
seems overkill.  We now simply define a structure which represents the
layout in the config space: the config space can now only be extended
at the end.

The main driver-visible changes:
1) We indicate what fields are present with an explicit feature bit.
2) Virtqueues are explicitly numbered, and not in the config space.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Rusty Russell
2008-02-04 23:49:56 -05:00
parent f35d9d8aae
commit a586d4f601
11 changed files with 278 additions and 279 deletions
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9
include/linux/lguest_launcher.h
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@@ -23,7 +23,12 @@
struct lguest_device_desc {
/* The device type: console, network, disk etc. Type 0 terminates. */
__u8 type;
/* The number of bytes of the config array. */
/* The number of virtqueues (first in config array) */
__u8 num_vq;
/* The number of bytes of feature bits. Multiply by 2: one for host
* features and one for guest acknowledgements. */
__u8 feature_len;
/* The number of bytes of the config array after virtqueues. */
__u8 config_len;
/* A status byte, written by the Guest. */
__u8 status;
@@ -31,7 +36,7 @@ struct lguest_device_desc {
};
/*D:135 This is how we expect the device configuration field for a virtqueue
* (type VIRTIO_CONFIG_F_VIRTQUEUE) to be laid out: */
* to be laid out in config space. */
struct lguest_vqconfig {
/* The number of entries in the virtio_ring */
__u16 num;